公开(公告)号：HUT65611A

公开(公告)日：1994-07-28

申请号：HU126293

申请日：1991-10-29

Applicant: IBM

Inventor： DESAI NARENDRA M ,  BEATTIE IRENE ,  VANOVER MICHAEL TERRELL ,  VOLTIN JOHN ALVIN

IPC: G06T11/00 ,  G09G5/06 ,  G06F3/14 ,  G09G5/14

Abstract: A video display system selectively controls by window the number of overlay planes, the number of overlay palettes, and the overlay/underlay plane masks in a graphics display. A logic/multiplex control 13, 11 translates overlay and underlay data patterns from a multiple plane VRAM 12, referenced to the graphics system frame buffer 9, into window specific patterns. The window related translation is conveyed to conventional RAMDACs 11 for raster scan synchronized digital-to-analog conversion. The translation as provided by the controller is responsive to data selectively and dynamicaliy written into a random access memory 14, thus providing translation of overlay/underlay data into window distinct and selective overlay/underlay palette functions.